chondroitin and copper-phthalocyanine

Synchrotron x-ray diffraction experiments indicate that corneas with macular corneal dystrophy (MCD) contain unusual 4.6-A periodic repeats thought to reside in proteoglycans or glycosaminoglycans. Recently the 4.6-A x-ray reflection was found to be significantly diminished after incubation of MCD specimens in buffer containing chondroitinase ABC or N-glycanase. We examined the sulfated proteoglycans in these glycosidase-digested MCD corneas.. Transmission electron microscopy was used in conjunction with cuprolinic blue-staining for sulfated proteoglycans.. Incubation of an MCD specimen in enzyme buffer left both small and large proteoglycan filaments in the stromal matrix, whereas incubation in the presence of chondroitinase ABC removed these molecules from the tissue. Incubation in buffer containing N-glycanase, on the other hand, removed the large proteoglycan filaments from the MCD stroma but left unaffected the small collagen-associated proteoglycans.. These results are consistent with the interpretation that 4.6-A periodic repeats in MCD corneas reside in large sulfated proteoglycan filaments (or aggregates thereof) that may contain chondroitin/dermatan sulfate and keratan sulfate or keratan components.

Topics: Chondroitin; Chondroitin Lyases; Coloring Agents; Corneal Dystrophies, Hereditary; Corneal Stroma; Culture Media; Dermatan Sulfate; Enzyme-Linked Immunosorbent Assay; Histocytochemistry; Humans; Indoles; Keratan Sulfate; Microscopy, Electron; Organometallic Compounds; Proteoglycans; X-Ray Diffraction

Proteoglycans (PGs) in bovine corneal stroma were stained with Cupromeronic Blue in 'critical-electrolyte-concentration' (CEC) methods for electron microscopy, and were located vis-à-vis collagen fibril a-e banding patterns. Keratanase and chondroitin ABC lyase digestion showed that a + c-band- and d + e-band-associated PGs were keratan sulphate-rich and chondroitin (dermatan) sulphate-rich respectively. The CEC pattern proved that the keratan sulphate PGs at the a and c bands differed. Comparison of their CECs with their behaviour on anion-exchange chromatography confirmed previous (indirect) attempts at identification [Scott & Haigh (1985) Biosci. Rep. 5, 765-774]. Similar arguments were applied to the dermatan sulphate PGs at the d and e bands. These results strongly support the one-PG-one-binding-site hypothesis [e.g. Scott (1988) Biochem. J. 252, 313-323]. Remarkable inter-species variations in the keratan sulphate PG patterns contrast with the relatively constant picture of dermatan sulphate PG-collagen fibril interactions.

Topics: Animals; Binding Sites; Cattle; Chondroitin; Chondroitin Sulfate Proteoglycans; Collagen; Coloring Agents; Cornea; Dermatan Sulfate; Electrolytes; Glycosaminoglycans; Indicators and Reagents; Indoles; Keratan Sulfate; Lumican; Microscopy, Electron; Organometallic Compounds; Proteoglycans; Rabbits